Past studies with animals have shown that the sorption of odorants (odor molecules) into the olfactory epithelium is altered by changing flow rates, and the way that the sorption is affected is greatly determined by the polarity of the odorant. A change in the sorption of odorants, therefore, alters the perception of odorants. Since flavor perception is a mixture of taste and retronasal olfaction, flavor perception is altered as well. Flavor perception and thus, retronasal olfaction, are important to nutrition and food intake, which can change with age and disease. Retronasal olfaction is the process of smelling from the mouth, in which odorants travel behind the palate to the posterior nares and enter the nasal cavity. This is different from orthonasal olfaction or sniffing, in which odorants enter the nasal cavity from the anterior nares. The overall research goal is to use electrophysiology to study how various food odorants with a wide range of chemical properties are affected by different air flow rates in the nasal cavity during the processes of orthonasal and retronasal olfaction. Both orthonasal and retronasal olfaction will be studied since odorants traveling through these two routes produce different sensations, particularly the magnitude of the sensations. The first aim is to test the effect of the polarity molecular properties of the food odorants on the size of the resulting electroolfactogram (EOG) responses in orthonasal and retronasal olfaction. A variety of food odorants with a range of polarities will be tested with a particular interest in fat odorants because retronasal olfaction may be differentially sensitive to the fat content in food, a potential factor with regard to the issues of flavor preferences and obesity. The second aim is to determine how the polarity of food odorants and the air flow rate in the nasal cavity work together to affect the magnitude of EOG responses for retronasal olfaction in addition to orthonasal olfaction. The third aim is to test the food odorants with multiple pulses of odor stimulation to try to simulate olfactory sensation during chewing and swallowing. The influence of flavor sensations as potential obstacles to dietary change and dietary adherence has not been a prominent subject in current research on health promotion, therapeutic diets, and weight loss, all of which are major issues for millions of Americans, especially the obese and the elderly. However, flavor sensations, which are a combination of taste and olfaction, are the most important factor in determining food choices. Flavor perceptions and, thus, olfactory perceptions should therefore be integral considerations in the development of population-specific dietary strategies for the prevention and treatment of obesity and chronic diseases.